1. Field of the Invention
This invention relates to a bulkhead fitting or outlet for connecting spray nozzles, drop tubes, drop hoses or the like to an irrigation pipeline wherein the irrigation pipe is lined with a plastic material.
2. Description of the Related Art
In mechanized irrigation systems such as center pivot irrigation systems or linear move irrigation systems, the main pipeline or water supply pipe is supported on a plurality of spaced-apart drive towers. To facilitate the sprinkling or spraying of water onto the area to be irrigated beneath the irrigation system, a plurality of spaced-apart sprinkler nozzles are connected to the water supply pipe. In some cases, the nozzles are positioned on the upper portion of the water supply pipe. In other instances, inverted, U-shaped drop tubes or drop hoses are used which extend from the water supply pipe to a location below the pipe with the lower end of the drop tube or drop hose having a sprinkler nozzle mounted thereon. Each of the sprinkler nozzles, drop tubes or drop hoses is normally placed in communication with the interior of the water supply pipe by first cutting an opening in the pipe at the desired location and then welding an internally threaded outlet to the exterior surface of the pipe so that the interior of the outlet communicates with the opening in the pipe, and then threadably inserting the nozzle or drop tube into the outlet. For example, see U.S. Pat. No. 5,938,127.
In many instances where the irrigation system is being used, the water to be irrigated is highly corrosive which substantially reduces the life of the irrigation system. In an effort to prevent the metal pipeline from coming into contact with the corrosive water being irrigated, the pipeline is sometimes lined with a polyethylene material which makes it impossible to weld the bulkhead fitting or outlet fitting to the pipe. In those systems where the pipeline is lined with a plastic material, drop hoses are normally used so that the corrosive water is discharged from the system below the pipeline.
Certain bulkhead fittings or outlets have been previously provided in poly-lined pipelines which do not require that the fittings or outlets be welded to the pipeline. However, the prior art bulkhead fittings are normally only useable with a pipe having a particular internal diameter. For example, a particular bulkhead fitting may be designed for use with a pipe having an eight inch internal diameter, but the same will not work with a pipe having a nine or ten inch internal diameter since pipes of different diameters have different internal radii.